I am using data I found in this http://www.tableausoftware.com/forum/polygon-files-structures post to create a shaded polygon map. Most of the map looks great, but there is some kind of error in the TX data points... I'm getting a unshaded triangle right in through the middle of texas. The thing that is boggling my mind is when I download the entire twbx file from the above link, the map looks fine... if I unpack that file and use the lat/long boundaries contained within for a new Tableau map, I get the error. I found another random shapefile formatted for Tableau on a different site and the exact same error occurred, in the exact same place. I'm stumped. Any help would be much appreciated.